WARNING - The Fox 60R/C and Fox 74R/C have several
unconventional features that require different handling from
other motors you have probably been accustomed to using. Read
this instruction manual completely before attempting to operate
or disassemble.

SUITABLE MODELS - The Fox 60R/C and Fox 784R/C have
been developed specifically for multi-channel radio model airplanes.
Stunt models weighing from 6 lbs. to 9 lbs. is the normal range.
Heavier models can be flown with some sacrifice in performance.

INSTALLATION - The Fox 60R/C and Fox74R/C are designed
for normal beam mounting. The mount dimensions are shown on the
drawing on the inside of this folder. 6-32 screws are recommended.
You may wish to install your engine radially against the firewall.
The casting has purposely been made rugged enough for the possibility.
Due to the unusual fuel injection carburetion used on the Fox
60R/C and Fox 74R/C the fuel tank mounting is not as critical
as with many other make motors. For practical purposes however,
the fuel bottle should be mounted not further than 6" aft
of the rear cover and not more than an inch above or below the
thrust line.

BREAK-IN - Your Fox 60R/C or Fox 74R/C has been carefully
made and tested at the factory. About the only practical purpose
served by a break-in period is to familiarize you with the controls
and adjustments.

PROPELLER TO USE - An 11-8 pitch propeller is recommended
for faster, clean models, while 12-7 or 12-6 and 13-5 propellers
seem to work better on the slower flying models. We recommend
that you use only wood propellers as most nylon propellers seem
unable to withstand the power of these engines for long, and
they shed blades with rather disastrous results.

FUEL - A Fox 60R/C and Fox 74R/C will run on a wide
variety of glow fuel. We have found a mixture of 1 gallon of
Duke's Fuel plus 1 gallon of commercial methanol to be excellent.
We have spent considerable effort to design this motor so that
it will run on a low castor oil content fuel. This reduces the
cost of the fuel, reduces the slobber on the side of the airplane,
and reduces the carbon inside the engine. Test engines have been
run satisfactorily on mixes as thin as 96% alcohol and 4% castor
oil. However, the cylinder wear rate seems to go up rather rapidly
with mixes containing less than 10% castor oil. If the maximum
power output is desired, higher nitro fuel such as Missile Mist
or Blast can be used either straight or thinned with methanol.
You should bear in mind that both Missile Mist and Blast contain
nitroethane to which only epoxy finishes seem totally resistant.

CARBURETOR ADJUSTMENTS - In the technical sense, the
Fox 60R/C and the Fox 74R/C engines are low pressure fuel injection
engines. The air is metered by a rotating throttle barrel, and
the fuel is metered by a progressive three-jet rotary valve system.
The idle jet feeds at all times. At the 25% throttle position
the intermediate jet starts feeding additional fuel into the
manifold. At 75% throttle position the high speed jet starts
feeding additional fuel into the manifold. Each jet has independently
adjustable flow valves. An even mixture adjustment throughout
the throttle range is accomplished by the shape of the air valve
which admits a quantity of air to match the fuel flow at that
throttle position. The bypass side horizontal screw is the high
speed mixture needle. The bypass side vertical screw is the idle
mixture needle. The exhaust side horizontal screw is the intermediate
mixture needle, which also accepts the fuel line. The exhaust
side vertical screw is the idle stop screw. We recommend this
adjustment procedure. Set the idle stop screw so the engine runs
at 3,000 RPM. Screw the idle mixture screw in leaning the mixture
until the engine threatens to stop. Richen the mixture slightly
and readjust the idle speed for 2,500 RPM. Next open the throttle
until the arm is in the 50% open position. Screw in the intermediate
jet adjustment until the engine again threatens to quit and back
the intermediate jet out slightly. For the high speed adjustment,
open the throttle wide and adjust the high speed needle for maximum
power. Then back it out until the engines slows approximately
400 RPM. If the tank is mounted further back than customary it
may be necessary to back the high speed jet out a bit further
to avoid the engine going over-lean in a climb attitude. The
throttle then should be moved back and forth through the carburetor
range to check for any lean spots or rich spots. The secret of
a reliable idling engine during touch and goes and taxiing is
to keep the intermediate and low speed adjustments as lean as
practical. On the other hand the high speed jet should be run
on the rich side to avoid over-heating and over-leaning as the
tank becomes emptied.

GLOW PLUGS - The Fox 60R/C and Fox 74R/C are equipped
with two glow plugs. The one on the exhaust side is a Fox R/C
Long plug and is positioned for the best idle. The one on the
bypass side is a Fox Heavy Duty Short Plug and is positioned
for maximum power. WARNING - If you use a non-recommended plug
on the by pass side it might hit the piston baffle and cause
all sorts of trouble.

50 FLIGHT INSPECTION - It is a good practice to examine
your engine closely every fifty flights or so. Remove the engine
from the plane. Thoroughly clean the exterior using a brush and
Stoddard solvent. Check all of the visible screws of tightness.
Replace both glow plugs unless they have been recently replaced.
Check carefully for excessive wear on any of the throttle or
exhaust components. If substantial wear is apparent, get your
order in for replacement parts before a crisis occurs. When a
cylinder loses compression for the first time, usually a new
set of rings will get you back in working order. The second time
both the rings and cylinder liner should be replaced.

DISASSEMBLY PROCEDURE - A thrust washer is fitted rather
tightly on the crankshaft and is held with a woodruff key. The
thrust washer can be removed by pulling it forward or toward
the spinner nut. However, in some cases a bit of effort will
be required. Removal of the head screws frees the cylinder head
and the cylinder liner can be lifted out. Four rear cover screws
will remove the rear cover. You will observe that the con rod
is held onto the crank pin by a knurled headed screw. This screw
has left-hand threads and can be removed by screwing clockwise
with a pair of pliers. You should not attempt to remove the piston
and rod assembly without removing the needle cage assembly. When
you pick out the needle cage assembly, needles will fly every
way so do this operation over a shoe box or similar container.
The rod and piston assembly can then be removed from the top.
The rod can be removed from the piston by removing either snap
ring and withdrawing the wrist pin. The upper needle cage assembly
is identical to the lower one, however you will not have the
needle flying problem if you keep the assembly in the rod. When
you re-assemble it a bit of vaseline or grease is very helpful
in holding the needles into the cage until you can get the assembly
together. The carburetor assembly can be removed from the crankcase
by removing the screw in the front end of the exhaust valve to
free the linkage, and then removing the two screws from the bottom
side of the crankcase.

We want your Fox 60R/C or Fox 74R/C to perform flawlessly
for you. Technical advice can be obtained directly from Duke
Fox by phoning Area 501 646-1656. It is our desire that dealers
who stock Fox parts be patronized, however any order placed directly
with us will be promptly shipped.